Method of forming a self-assembled molecular layer

ABSTRACT

A method includes chemically bonding a polymeric material to a self-assembled molecular film that is chemically bonded to a surface of a substrate. The self-assembled molecular film includes one or more defect sites and a plurality of active device molecules, each of the plurality of active device molecules including a molecular switching moiety having a self-assembling connecting group at one end of the moiety and a linking group at an opposed end of the moiety. The polymeric material chemically bonds to at least some of the linking groups of the plurality of active device molecules, causing the formation of the self-assembled molecular layer covering the plurality of active device molecules and the defect site(s).

BACKGROUND

The present invention relates generally to molecular electronics, andmore particularly to the fabrication of self-assembled molecular layers.

Molecular devices comprising two electrodes (for example, a bottomelectrode and a top electrode) and a molecular switching layer/film atthe junction of the two electrodes are known. Such devices may beuseful, for example, in the fabrication of devices based on electricalswitching, such as molecular wire crossbar interconnects for signalrouting and communications, molecular wire crossbar memory, molecularwire crossbar logic employing programmable logic arrays,multiplexers/demultiplexers for molecular wire crossbar networks,molecular wire transistors, and the like. Such devices may further beuseful, for example, in the fabrication of devices based on opticalswitching, such as displays, electronic books, rewritable media,electrically tunable optical lenses, electrically controlled tinting forwindows and mirrors, optical crossbar switches (for example, for routingsignals from one of many incoming channels to one of many outgoingchannels), and the like.

Typically, the molecular switching layer/film comprises an organicmolecule that, in the presence of an electrical (E) field, switchesbetween two or more energetic states, such as by an electrochemicaloxidation/reduction (redox) reaction or by a change in the band gap ofthe molecule induced by the applied E-field.

It is important to form a good electrical contact between the electrodeand the molecular switching layer in order to fabricate operativemolecular devices. Molecules with special chemical end groups are ableto form direct chemical bonds with metal/semiconductor electrodes toform a self-assembled monolayer/molecular layer (SAM), which may have agood electrical contact with an electrode(s). However, thisself-assembled molecular layer formed on the surface of the electrodemay generally be prone to a high density of defects. If a secondelectrode is formed on the molecular layer, then an electrical short mayoccur between the first and second electrode through the defects in theself-assembled molecular layer.

As such, there is a need for providing a high density molecularswitching layer on an electrode(s), which layer also bonds well with theelectrode. Further, there is a need for reducing and/or substantiallyeliminating electrical short circuit problems potentially associatedwith molecular electronic devices.

SUMMARY

Embodiment(s) of the present invention substantially solve the drawbacksenumerated above by providing a method for forming a self-assembledmolecular layer. The method includes chemically bonding a polymericmaterial to a self-assembled molecular film chemically bonded to asurface of a substrate. The self-assembled molecular film includes oneor more defect sites and a plurality of active device molecules, each ofthe plurality of active device molecules including a molecular switchingmoiety having a self-assembling connecting group at one end of themoiety and a linking group at an opposed end of the moiety. Thepolymeric material chemically bonds to at least some of the linkinggroups of the plurality of active device molecules, thereby forming theself-assembled molecular layer covering a plurality of active devicemolecules and the one or more defect sites.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects, features and advantages of embodiments of the present inventionwill become apparent by reference to the following detailed descriptionand drawings, in which like reference numerals correspond to similar,though not necessarily identical components. For the sake of brevity,reference numerals having a previously described function may notnecessarily be described in connection with subsequent drawings in whichthey appear.

FIG. 1A is a schematic representation of two crossed wires, with atleast one molecule at the intersection of the two wires;

FIG. 1B is a perspective elevational view, depicting the crossed-wiredevice shown in FIG. 1A;

FIG. 2 is a schematic representation of a two-dimensional array ofswitches, depicting a 6×6 crossbar switch;

FIGS. 3A and 3B are schematic flow diagrams depicting an embodiment of amethod of forming a self-assembled molecular layer;

FIGS. 4A and 4B is similar to FIG. 3, but depicts an alternateembodiment of a method of the present invention; and

FIGS. 5A and 5B is similar to FIG. 3, but depicts a further alternateembodiment of a method of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention advantageously use a novel conceptof providing a self-assembled molecular layer/monolayer, which may actas a protective layer. This novel concept takes advantage of theadvantageous qualities of self-assembly techniques (e.g. good electricalcontact due to chemical bonding) while substantially eliminatingproblems that may, in some instances, be associated with thesetechniques.

The method according to embodiments of the present invention providesorienting a self-assembled molecular layer that may be dense and highlyuniform on a molecular film such that the self-assembled molecular layeracts as a barrier between the molecular film and any subsequentlydeposited metal.

Referring now to FIGS. 1A-1B, a crossed wire switching device 10includes two wires 12, 14, each either a metal and/or semiconductorwire, that are crossed at some substantially non-zero angle. Disposedbetween wires 12, 14 is a layer 16 of molecules and/or molecularcompounds, denoted R. The particular molecules (active device molecules)18 that are sandwiched at the intersection (also interchangeablyreferred to herein as a junction) of the two wires 12, 14 are identifiedas switch molecules R_(S).

There are generally two primary methods of operating such switches 10,depending on the nature of the switch molecules 18. The molecularswitching layer 16 includes a switch molecule 18 (for example, anorganic molecule) that, in the presence of an electrical (E) field,switches between two or more energetic states, such as by anelectrochemical oxidation/reduction (redox) reaction or by a change inthe band gap of the molecule induced by the applied E-field.

In the former case, when an appropriate voltage is applied across thewires 12, 14, the switch molecules R_(S) are either oxidized or reduced.When a molecule is oxidized (reduced), then a second species is reduced(oxidized) so that charge is balanced. These two species are then calleda redox pair. One example of this device would be for one molecule to bereduced, and then a second molecule (the other half of the redox pair)would be oxidized. In another example, a molecule is reduced, and one ofthe wires 12, 14 is oxidized. In a third example, a molecule isoxidized, and one of the wires 12, 14 is reduced. In a fourth example,one wire 12, 14 is oxidized, and an oxide associated with the other wire14, 12 is reduced. In such cases, oxidation or reduction may affect thetunneling distance or the tunneling barrier height between the twowires, thereby exponentially altering the rate of charge transportacross the wire junction, and serving as the basis for a switch.Examples of molecules 18 that exhibit such redox behavior includerotaxanes, pseudo-rotaxanes, and catenanes; see, e.g., U.S. Pat. No.6,459,095, entitled “Chemically Synthesized and Assembled ElectronicDevices”, issued Oct. 1, 2002, to James R. Heath et al, the disclosureof which is incorporated herein by reference in its entirety.

Further, the wires 12, 14 may be modulation-doped by coating theirsurfaces with appropriate molecules—either electron-withdrawing groups(Lewis acids, such as boron trifluoride (BF₃)) or electron-donatinggroups (Lewis bases, such as alkylamines) to make them p-type or n-typeconductors, respectively. FIG. 1B depicts a coating 20 on wire 12 and acoating 22 on wire 14. The coatings 20, 22 may be modulation-dopingcoatings, tunneling barriers (e.g., oxides), or other nano-scalefunctionally suitable materials. Alternatively, the wires 12, 14themselves may be coated with one or more R species 16, and where thewires cross, R_(S) 18 is formed. Or yet alternatively, the wires 12, 14may be coated with molecular species 20, 22, respectively, for example,that enable one or both wires 12, 14 to be suspended to form colloidalsuspensions, as discussed below. Details of such coatings are providedin above-referenced U.S. Pat. No. 6,459,095.

In the latter case, examples of molecule 18 based on field inducedchanges include E-field induced band gap changes, such as disclosed andclaimed in patent application Ser. No. 09/823,195, filed Mar. 29, 2001,published as Publication No. 2002/0176276 on Nov. 28, 2002, whichapplication is incorporated herein by reference in its entirety.Examples of molecules used in the E-field induced band gap changeapproach include molecules that evidence molecular conformation changeor an isomerization; change of extended conjugation via chemical bondingchange to change the band gap; or molecular folding or stretching.

Changing of extended conjugation via chemical bonding change to changethe band gap may be accomplished in one of the following ways: chargeseparation or recombination accompanied by increasing or decreasing bandlocalization; or change of extended conjugation via charge separation orrecombination and π-bond breaking or formation.

The formation of micrometer scale and nanometer scale crossed wireswitches 10 uses either a reduction-oxidation (redox) reaction to forman electrochemical cell or uses E-field induced band gap changes to formmolecular switches. In either case, the molecular switches typicallyhave two states, and may be either irreversibly switched from a firststate to a second state or reversibly switched from a first state to asecond state. In the latter case, there are two possible conditions:either the electric field may be removed after switching into a givenstate, and the molecule will remain in that state (“latched”) until areverse field is applied to switch the molecule back to its previousstate; or removal of the electric field causes the molecule to revert toits previous state, and hence the field must be maintained in order tokeep the molecule in the switched state until it is desired to switchthe molecule to its previous state.

Color switch molecular analogs, particularly based on E-field inducedband gap changes, are also known; see, e.g., U.S. application Ser. No.09/844,862, filed Apr. 27, 2001.

Referring now to FIG. 2, the switch 10 may be replicated in atwo-dimensional array to form a plurality/array 24 of switches 10 toform a crossbar switch. FIG. 2 depicts a 6×6 array 24. However, it is tobe understood that the embodiments herein are not to be limited to theparticular number of elements, or switches 10, in the array 24. Accessto a single point, e.g., 2 b, is done by impressing voltage on wires 2and b to cause a change in the state of the molecular species 18 at thejunction thereof, as described above. Thus, access to each junction isreadily available for configuring those that are pre-selected. Detailsof the operation of the crossbar switch array 24 are further discussedin U.S. Pat. No. 6,128,214, entitled “Molecular Wire Crossbar Memory”,issued on Oct. 3, 2000, to Philip J. Kuekes et al., which isincorporated herein by reference in its entirety.

Referring now to FIGS. 3A and 3B, a method of forming a self-assembledmolecular layer 30 includes chemically bonding one or more active devicemolecules 18 to a surface of a substrate 25 to form a self-assembledmolecular film 29. Chemically bonding the active device molecules 18 tothe substrate 25 may be accomplished by a self-assembled mono-layer(SAM) process. Using this process, self-assembling connecting groups(SCG) 28 of the active device molecules 18 bond to the substrate 25surface.

It is to be understood that the substrate 25 may be made of any suitableconductive or semi-conductive material. In an embodiment, the substrate25 is a bottom electrode 38. It is to be understood that in an opticalapplication, the substrate 25 may be a non-electrode material.

In an embodiment, the active device molecule 18 includes a switchingmoiety (MD) 26 having a linking group (ILGA) 27 and the previouslymentioned self-assembling connecting group 28 at opposed ends thereof.

The molecular switching moiety 26 is an optically switchable molecularfunctional unit and/or an electrically switchable molecular functionalunit. It is to be understood that the switching moiety 26 may be anysuitable moiety, however, in an embodiment, the moiety 26 includes atleast one of saturated hydrocarbons, unsaturated hydrocarbons,substituted hydrocarbons, heterocyclic systems, organometallic complexsystems, and/or mixtures thereof.

In an embodiment, the switching moiety 26 includes a moiety that, in thepresence of an electric field, undergoes oxidation/reduction, and/orexperiences a band gap change. In one embodiment, the switching moiety26 undergoes oxidation/reduction and includes at least one of rotaxanes,pseudo-rotaxanes, catenanes, and mixtures thereof. An example of aswitching moiety 26 that undergoes a band gap change in the presence ofan external electrical field is described in U.S. Pat. No. 6,674,932granted to Zhang et al. on Jan. 6, 2004, the specification of which ishereby incorporated herein by reference in its entirety.

The linking group 27 may be bonded to one end of the switching moiety 26such that it is adapted to bond to the self-assembled molecular layer 30(shown in FIG. 3B). It is to be understood that the linking group 27 maybe, but is not limited to at least one of multivalent hetero atomsselected from the group consisting of C, N, O, S, and P; functionalgroups containing the hetero atoms and selected from the groupconsisting of NH₂, NH-alkyl, and NH-aryl; pyridine; heterocycliccompounds including at least one nitrogen atom; carboxylic acids;sulfuric acids; phosphoric acids; and/or mixtures thereof.

The self-assembling connecting group 28 may be bonded to the opposed endof the switching moiety 26, such that it is capable of bonding to thesubstrate 25 surface. Examples of suitable self-assembling connectinggroups 28 include, but are not limited to at least one of multivalenthetero atoms selected from the group consisting of C, N, O, S, and P;functional groups containing the hetero atoms and selected from thegroup consisting of SH, S-acyl, S-S-alkyl, OH, NH₂, NH-alkyl, NH-aryl,NH-acyl; heterocyclic compounds; pyridine and derivatives thereof (anon-limitative example of which includes substituted pyridines, such asN,N-dimethylamino pyridine); carboxylic acids; derivatives thereof(non-limitative examples of which include carboxylic esters, amides,nitrites, and/or the like); amines; alkyl amines; and mixtures thereof.

Upon bonding the active device molecules 18 to the substrate 25 via aSAM process, the self-assembled molecular film 29 is formed. Due in partto the SAM process, the self-assembled molecular film 29 may be aloosely packed mono-layer film that contains one or more defect sites 32that may cause short circuits when electrical contacts (e.g. topelectrode(s) 34) are deposited on the film 29.

Referring now to FIG. 3B, the self-assembled molecular layer 30 isformed on the self-assembled molecular film 29 such that it covers theplurality of active device molecules 18 and the one or more defectsite(s) 32. It is believed, without being bound to any theory, that theself-assembled molecular layer 30 is adapted to protect the plurality ofactive device molecules 18 and the at least one defect site 32 frompotential deleterious effects (e.g. metal penetration, electricalshorting, and undesirable chemical reaction(s)) associated with theaddition of a metal layer (e.g. top electrode(s) 34).

The self-assembled molecular layer 30 may be formed by chemicallybonding a conductive or non-conductive polymeric material within asolution to at least some of the linking groups 27 of the active devicemolecules 18 in the self-assembled molecular film 29.

It is to be understood that chemically bonding the polymeric material tolinking groups 27 may be accomplished by ionic bonding, covalent bonding(e.g. substitution reaction) and/or coordination bonding (e.g. metalcomplex formation).

In an embodiment where ionic bonding is used to form the self-assembledmolecular layer 30, the self-assembled molecular film 29 bonded to thesubstrate 25 is immersed into a solution containing the polymericmaterial. It is to be understood that any suitable polymeric material insolution may be used. In an embodiment, the polymeric material solutioncontains at least one of polyvinylamines, polyvinylpyridines, aminosubstituted polyacrylates, polyacrylic acids, polymethacrylic acids,polystyrene sulfuric acids, and/or mixtures thereof. It is to be furtherunderstood that, upon immersion into the solution, an acid-base reaction(ionization reaction) takes place between the polymeric material and thelinking group 27. Without being bound to any theory, it is believedthat, due in part to the exothermic acid-base reaction, the polymericmaterial may self-organize to achieve a substantially stable and lowenergy state and to form the substantially dense and highly uniformself-assembled molecular layer 30. When using ionic bonding, it iscontemplated that the linking groups 27 of the active device molecules18 and functional groups ILGB of the polymeric material are selected sothat ionic bonds form between the two groups.

It is to be understood that in an embodiment utilizing ionic bonding,the polymeric material may behave as if it were cross-linked, thus theinterlocking ionic molecular layer 30 may substantially improve thestructural rigidity, and may advantageously enhance the reliabilityand/or durability of the device 10 in which the molecular layer 30 isused.

In an embodiment employing a non-conductive polymeric material andelectrical switching, the final self-assembled molecular layer 30 mayhave a thickness of less than about 2 nm so that electronic tunnelingmay occur. In a further embodiment, the thickness is less than about 1nm. In an embodiment employing a non-conductive polymeric material andoptical switching, the final self-assembled molecular layer 30 may havea thickness that is greater than about 2 nm. In this embodiment, thethickness of the self assembled molecular layer 30 may range betweenabout 2 nm and about 10 μm.

Further, an embodiment of the method may optionally include the step ofdepositing a metal layer (e.g. top electrode 34) on the self-assembledmolecular layer 30. Any suitable metal layer (non-limitative examples ofwhich include titanium, aluminum, platinum, alloys thereof, mixturesthereof, and/or the like) or top electrode 34 may be selected. It iscontemplated as being within the purview of the present invention thatany suitable deposition technique may be used to form the top electrode34, including, but not limited to an evaporative metal depositionprocess, a thermal metal deposition process, a sputtering process,and/or the like.

It is believed that, without being bound to any theory, thesubstantially dense and uniform self-assembled molecular layer 30advantageously substantially prevents metal penetration duringevaporative metal deposition when the top electrode 34 is formed or whensubsequent metal diffusion occurs. The self-assembled molecular layer 30may also advantageously prevent a chemical reaction between the activedevice molecules 18 and the metal layer/top electrode 34, and/or otherenvironmental contaminants.

In a further embodiment, chemical bonding may be formed in an interface36 between the top electrode 34 and the self-assembled molecular layer30 during the deposition of the top electrode 34 via a thermal metaldeposition process.

It is to be understood that in this embodiment, the self-assembledmolecular layer 30 may become metallized. A metallized self-assembledmolecular layer 30 may advantageously enhance the electricalconductivity, reduce and/or eliminate the possibility of interfacialcharge trapping, and improve the mechanical integrity of the topelectrode 34.

A non-limitative embodiment of the method is shown in FIGS. 4A and 4B.In this embodiment, the active device molecules 18 have thiol (S) as theself-assembling connecting group 28, and COOH as the linking group 27.The active device molecules 18 are covalently bonded via the connectinggroup(s) 28 to a substrate 25 (non-limitative examples of which includebottom electrodes 38, gold, platinum, silver, copper, alloys thereof,mixtures thereof, or the like) to form the self-assembled molecular film29. As depicted in FIG. 4A, at least one defect site 32 is present inthe film 29.

The arrow between FIGS. 4A and 4B represents immersing the film 29bonded to the substrate 25 into a diluted (about 0.1% or less)polyvinylamine solution. The amines of the polymer solution ionicallybond with the COOH linking groups 27 of the active device molecules 18in the film 29. The bonding of these groups forms the self-assembledmolecular layer 30.

A metal layer or top electrode 34 may then be deposited/formed on theself-assembled molecular layer 30.

A second non-limitative embodiment of the method is shown in FIGS. 5Aand 5B. In this embodiment, the active device molecules 18 have thiol(S) as the self-assembling connecting group 28, and NH₂ as the linkinggroup 27. The active device molecules 18 are covalently bonded via theconnecting group(s) 28 to a substrate 25 (non-limitative examples ofwhich include bottom electrodes 38, gold, platinum, silver, copper,alloys thereof, mixtures thereof, and/or the like) to form theself-assembled molecular film 29. As depicted in FIG. 5A, at least onedefect site 32 is present in the film 29.

The arrow between FIGS. 5A and 5B represents immersing the film 29bonded to the substrate 25 into a diluted (about 0.1% or less)polystyrene sulfuric acid solution. The phenyl sulfuric acid groups ofthe polymer solution ionically bond with the NH₂ linking groups 27 ofthe active device molecules 18 in the film 29. The bonding of thesegroups forms the self-assembled molecular layer 30.

A metal layer or top electrode 34 may then be deposited on theself-assembled molecular layer 30.

An embodiment of a plurality of molecules (self-assembled molecules) 40includes a plurality of active device molecules 18, each having aswitching moiety 26 with a linking group 27 and a self-assemblingconnecting group 28 at opposed ends of the moiety 26. A polymericmaterial layer as previously described is chemically bonded to at leastsome of the linking groups 27 of the active device molecules 18 to formthe self-assembled molecular layer 30. It is to be understood that themolecule(s) 40 may be used in a variety of applications, including, butnot limited to a molecular switching device 10.

An embodiment of a crossed wire molecular device 24 includes a pluralityof bottom electrodes 38, a plurality of top electrodes 34 crossing thebottom electrodes 38 at a non-zero angle, a self-assembled molecularfilm 29 formed from a plurality of active device molecules 18 bonded tothe bottom electrode 38, and a self-assembled molecular layer 30 bondedto the self-assembled molecular film 29. The self-assembled molecularlayer 30 is bonded to the self-assembled molecular film 29 such that theactive device molecules 18 and the defect site(s) 32 are covered. Thefilm 29 and layer 30 are operatively disposed in at least one junctionformed where one electrode 34, 38 crosses another electrode 38, 34.

A non-limitative embodiment of a method of forming the crossed wiremolecular device 24 is as follows. The self-assembled molecular film 29is chemically bonded to the surface of at least one of the plurality ofbottom electrodes 38. A polymeric material within a solution ischemically bonded to at least some of the linking groups 27 of theactive device molecules 18 to form the self-assembled molecular layer 30covering the plurality of active device molecules 18 and the one or moredefect site(s) 32. The method may further include forming one of theplurality of top electrodes 34, crossing the one of the plurality ofbottom electrodes 38 at the non-zero angle, thereby forming the junctiontherebetween. The molecular film 29 and the molecular layer 30 arethereby operatively disposed at the junction.

While several embodiments have been described in detail, it will beapparent to those skilled in the art that the disclosed embodiments maybe modified. Therefore, the foregoing description is to be consideredexemplary rather than limiting.

1. A method for forming a self-assembled molecular layer, comprising thestep of chemically bonding a polymeric material to a self-assembledmolecular film chemically bonded to a surface of a substrate, theself-assembled molecular film including at least one defect site and aplurality of active device molecules, each of the plurality of activedevice molecules including a molecular switching moiety having aself-assembling connecting group at one end of the moiety and a linkinggroup at an opposed end of the moiety, wherein the polymeric materialchemically bonds to at least some of the linking groups of the pluralityof active device molecules, thereby forming the self-assembled molecularlayer covering the plurality of active device molecules and the at leastone defect site.
 2. The method as defined in claim 1 wherein chemicallybonding the polymeric material is accomplished by immersing theself-assembled molecular film bonded to the substrate surface into asolution containing the polymeric material.
 3. The method as defined inclaim 2 wherein the solution containing the polymeric material comprisesat least one of polyvinylamines, polyvinylpyridines, amino substitutedpolyacrylates, polyacrylic acids, polymethacrylic acids, polystyrenesulfuric acids, and mixtures thereof.
 4. The method as defined in claim1 wherein chemically bonding the polymeric material is accomplished byat least one of a substitution reaction and an ionization reaction. 5.The method as defined in claim 1 wherein chemically bonding thepolymeric material is accomplished by forming a metal complex formation.6. The method as defined in claim 1 wherein the substrate is a bottomelectrode.
 7. The method as defined in claim 6, further comprising thestep of depositing a top electrode on the self-assembled molecularlayer.
 8. The method as defined in claim 1, further comprising the stepof depositing a metal layer on the self-assembled molecular layer. 9.The method as defined in claim 1 wherein the molecular switching moietyis at least one of an optically switchable molecular functional unit andan electrically switchable molecular functional unit.
 10. The method asdefined in claim 7 wherein the molecular switching moiety comprises atleast one of saturated hydrocarbons, unsaturated hydrocarbons,substituted hydrocarbons, heterocyclic systems, organometallic complexsystems, and mixtures thereof.
 11. The method as defined in claim 1wherein the linking group comprises at least one at least one ofmultivalent hetero atoms selected from the group consisting of C, N, O,S, and P; functional groups containing the hetero atoms and selectedfrom the group consisting of NH₂, NH-alkyl, and NH-aryl; pyridine;heterocyclic compounds including at least one nitrogen atom; carboxylicacids; sulfuric acids; phosphoric acids; and mixtures thereof.
 12. Themethod as defined in claim 1 wherein the self-assembling connectinggroup comprises at least one of multivalent hetero atoms selected fromthe group consisting of C, N, O, S, and P; functional groups containingthe hetero atoms and selected from the group consisting of SH, S-acyl,S-S-alkyl, OH, NH₂, NH-alkyl, NH-aryl, NH-acyl; heterocyclic compounds;pyridine, substituted pyridines; carboxylic acids; carboxylic esters;amides; nitrites; amines; alkyl amines; and mixtures thereof.
 13. Amethod of forming a crossed wire molecular device comprising a pluralityof bottom electrodes, a plurality of top electrodes crossing the bottomelectrodes at a non-zero angle, a self-assembled molecular filmchemically bonded to a surface of each of the bottom electrodes, theself-assembled molecular film including at least one defect site and aplurality of active device molecules, each of the plurality of activedevice molecules including a molecular switching moiety having aself-assembling connecting group and a linking group opposed endsthereof, and a self-assembled molecular layer chemically bonded to theself-assembled molecular film, the self-assembled molecular film and theself-assembled molecular layer operatively disposed in at least onejunction formed where one electrode crosses an other electrode, themethod comprising the steps of: chemically bonding the self-assembledmolecular film to the surface of one of the plurality of bottomelectrodes; chemically bonding a polymeric material within a solution toat least some of the linking groups of the plurality of active devicemolecules, thereby forming the self-assembled molecular layer coveringthe plurality of active device molecules and the at least one defectsite; and forming one of the plurality of top electrodes, crossing theone of the plurality of bottom electrodes at the non-zero angle, therebyforming the at least one junction therebetween, wherein theself-assembled molecular layer is chemically bonded on a surface of theone of the plurality of top electrodes.
 14. The method as defined inclaim 13 wherein chemically bonding the polymeric material isaccomplished by immersing the self-assembled molecular film bonded tothe surface of one of the plurality of bottom electrodes into a solutioncontaining the polymeric material.
 15. The method as defined in claim 14wherein the polymeric material forms ionic bonds with at least some ofthe linking groups of the plurality of active device molecules.
 16. Themethod as defined in claim 13 wherein the solution containing thepolymeric material comprises at least one of polyvinylamines,polyvinylpyridines, amino substituted polyacrylates, polyacrylic acids,polymethacrylic acids, polystyrene sulfuric acids, and mixtures thereof.17. The method as defined in claim 13 wherein chemically bonding thepolymeric material is accomplished by a substitution reaction.
 18. Themethod as defined in claim 13 wherein chemically bonding the polymericmaterial is accomplished by forming a metal complex formation.
 19. Themethod as defined in claim 13 wherein the molecular switching moiety isat least one of an optically switchable molecular functional unit and anelectrically switchable molecular functional unit.
 20. The method asdefined in claim 19 wherein the molecular switching moiety comprises atleast one of saturated hydrocarbons, unsaturated hydrocarbons,substituted hydrocarbons, heterocyclic systems, organometallic complexsystems, and mixtures thereof.
 21. The method as defined in claim 13wherein the linking group comprises at least one at least one ofmultivalent hetero atoms selected from the group consisting of C, N, O,S, and P; functional groups containing the hetero atoms and selectedfrom the group consisting of NH₂, NH-alkyl, and NH-aryl; pyridine;heterocyclic compounds including at least one nitrogen atom; carboxylicacids; sulfuric acids; phosphoric acids; and mixtures thereof.
 22. Themethod as defined in claim 13 wherein the self-assembling connectinggroup comprises at least one of multivalent hetero atoms selected fromthe group consisting of C, N, O, S, and P; functional groups containingthe hetero atoms and selected from the group consisting of SH, S-acyl,S-S-alkyl, OH, NH₂, NH-alkyl, NH-aryl, NH-acyl; heterocyclic compounds;pyridine; substituted pyridines; carboxylic acids; carboxylic esters;amides; nitrites; amines; alkyl amines; and mixtures thereof.
 23. Themethod as defined in claim 13 wherein the polymeric material isnon-conductive and wherein the self-assembled molecular layer has athickness less than about 2 nm and is adapted to provide an electricallyconductive path to the self-assembled molecular film.
 24. The method asdefined in claim 23 wherein the thickness is less than about 1 nm. 25.The method as defined in claim 23 wherein the self-assembled molecularlayer is adapted to protect the plurality of active device molecules andthe at least one defect site.
 26. The method as defined in 13 whereinduring the step of forming one of the plurality of top electrodes, theself-assembled molecular layer becomes metallized.
 27. A plurality ofmolecules, comprising: a plurality of active device molecules, each ofthe active device molecules including: a switching moiety; aself-assembling connecting group at one end of the switching moiety; anda linking group at an opposed end of the switching moiety; at least onedefect site disposed between the plurality of active device molecules;and a self-assembled molecular layer chemically bonded to the pluralityof active device molecules via at least some of the linking groups. 28.The plurality of molecules as defined in claim 27 wherein the switchingmoiety is at least one of an optically switchable molecular functionalunit and an electrically switchable molecular functional unit.
 29. Theplurality of molecules as defined in claim 28 wherein the switchingmoiety comprises at least one of saturated hydrocarbons, unsaturatedhydrocarbons, substituted hydrocarbons, heterocyclic systems,organometallic complex systems, and mixtures thereof.
 30. The pluralityof molecules as defined in claim 27 wherein the linking group comprisesat least one at least one of multivalent hetero atoms selected from thegroup consisting of C, N, O, S, and P; functional groups containing thehetero atoms and selected from the group consisting of NH₂, NH-alkyl,and NH-aryl; pyridine; heterocyclic compounds including at least onenitrogen atom; carboxylic acids; sulfuric acids; phosphoric acids; andmixtures thereof.
 31. The plurality of molecules as defined in claim 27wherein the self-assembling connecting group comprises at least one ofmultivalent hetero atoms selected from the group consisting of C, N, O,S, and P; functional groups containing the hetero atoms and selectedfrom the group consisting of SH, S-acyl, S-S-alkyl, OH, NH₂, NH-alkyl,NH-aryl, NH-acyl; heterocyclic compounds; pyridine; substitutedpyridines; carboxylic acids; carboxylic esters; amides; nitrites;amines; alkyl amines; and mixtures thereof.
 32. The plurality ofmolecules as defined in claim 27 wherein the self-assembled molecularlayer comprises at least one of a non-conductive polymer, a conductivepolymer, and mixtures thereof.
 33. The plurality of molecules as definedin claim 32 wherein the self-assembled molecular layer comprises anon-conductive polymer, has a thickness less than about 2 nm, and isadapted to provide an electrically conductive path to the plurality ofmolecules.
 34. The plurality of molecules as defined in claim 27 whereinthe self-assembled molecular layer comprises at least one ofpolyvinylamines, polyvinylpyridines, amino substituted polyacrylates,polyacrylic acids, polymethacrylic acids, polystyrene sulfuric acids,and mixtures thereof.
 35. The plurality of molecules as defined in claim27 wherein the self-assembling connecting group is chemically bonded toa bottom electrode, and the self-assembled molecular layer is chemicallybonded to a top electrode.
 36. The plurality of molecules as defined inclaim 27 wherein the self-assembled molecular layer is chemically bondedto the linking group by one of ionic bonding, covalent bonding, andcoordination bonding.
 37. A molecular switching device, comprising: atleast one bottom electrode; at least one top electrode, the topelectrode crossing the bottom electrode at a non-zero angle, therebyforming a junction; and a plurality of self-assembled moleculesoperatively disposed in the junction, the plurality of self-assembledmolecules including: a plurality of active device molecules, each of theactive device molecules including: a switching moiety; a self-assemblingconnecting group at one end of the switching moiety; and a linking groupat an opposed end of the switching moiety; at least one defect sitedisposed between the plurality of active device molecules; and aself-assembled molecular layer chemically bonded to the plurality ofactive device molecules via at least some of the linking groups.
 38. Themolecular switching device as defined in claim 37 wherein the switchingmoiety is at least one of an optically switchable molecular functionalunit and an electrically switchable molecular functional unit.
 39. Themolecular switching device as defined in claim 38 wherein the switchingmoiety comprises at least one of saturated hydrocarbons, unsaturatedhydrocarbons, substituted hydrocarbons, heterocyclic systems,organometallic complex systems, and mixtures thereof.
 40. The molecularswitching device as defined in claim 37 wherein the linking groupcomprises at least one at least one of multivalent hetero atoms selectedfrom the group consisting of C, N, O, S, and P; functional groupscontaining the hetero atoms and selected from the group consisting ofNH₂, NH-alkyl, and NH-aryl; pyridine; heterocyclic compounds includingat least one nitrogen atom; carboxylic acids; sulfuric acids; phosphoricacids; and mixtures thereof.
 41. The molecular switching device asdefined in claim 37 wherein the self-assembling connecting groupcomprises at least one of multivalent hetero atoms selected from thegroup consisting of C, N, O, S, and P; functional groups containing thehetero atoms and selected from the group consisting of SH, S-acyl,S-S-alkyl, OH, NH₂, NH-alkyl, NH-aryl, NH-acyl; heterocyclic compounds;pyridine; substituted pyridines; carboxylic acids; carboxylic esters;amides; nitriles; amines; alkyl amines; and mixtures thereof.
 42. Themolecular switching device as defined in claim 37 wherein theself-assembled molecular layer comprises at least one of anon-conductive polymer, a conductive polymer, and mixtures thereof. 43.The molecular switching device as defined in claim 42 wherein theself-assembled molecular layer comprises a non-conductive polymer, has athickness less than about 2 nm, and is adapted to provide anelectrically conductive path to the plurality of self-assembledmolecules.
 44. The molecular switching device as defined in claim 37wherein the self-assembled molecular layer comprises at least one ofpolyvinylamines, polyvinylpyridines, amino substituted polyacrylates,polyacrylic acids, polymethacrylic acids, polystyrene sulfuric acids,and mixtures thereof.
 45. The molecular switching device as defined inclaim 37 wherein the self-assembled molecular layer is chemically bondedto the at least some of the linking groups by one of ionic bonding,covalent bonding, and coordination bonding.
 46. The molecular switchingdevice as defined in claim 37 wherein the self-assembled molecular layeris adapted to protect the at least one defect site.